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    <div id="content" role="main">
      <h1>Source code for isek.node.etcd_registry</h1><div class="highlight"><pre>
<span></span><code><span id="line-1"><span class="kn">import</span><span class="w"> </span><span class="nn">json</span>
</span><span id="line-2"><span class="kn">from</span><span class="w"> </span><span class="nn">typing</span><span class="w"> </span><span class="kn">import</span> <span class="n">Optional</span><span class="p">,</span> <span class="n">Dict</span><span class="p">,</span> <span class="n">Any</span> <span class="c1"># Added Any</span>
</span><span id="line-3"><span class="kn">import</span><span class="w"> </span><span class="nn">base64</span>
</span><span id="line-4">
</span><span id="line-5"><span class="kn">import</span><span class="w"> </span><span class="nn">etcd3</span> <span class="c1"># type: ignore # Assuming etcd3 might not have type stubs</span>
</span><span id="line-6"><span class="kn">from</span><span class="w"> </span><span class="nn">ecdsa.keys</span><span class="w"> </span><span class="kn">import</span> <span class="n">SigningKey</span><span class="p">,</span> <span class="n">VerifyingKey</span>
</span><span id="line-7"><span class="kn">from</span><span class="w"> </span><span class="nn">ecdsa.curves</span><span class="w"> </span><span class="kn">import</span> <span class="n">NIST256p</span>
</span><span id="line-8"><span class="kn">from</span><span class="w"> </span><span class="nn">ecdsa.util</span><span class="w"> </span><span class="kn">import</span> <span class="n">sigencode_der</span><span class="p">,</span> <span class="n">sigdecode_der</span> <span class="c1"># For deterministic signatures if needed</span>
</span><span id="line-9"><span class="c1"># from ecdsa.errors import BadSignatureError</span>
</span><span id="line-10"><span class="kn">from</span><span class="w"> </span><span class="nn">ecdsa</span><span class="w"> </span><span class="kn">import</span> <span class="n">BadSignatureError</span>
</span><span id="line-11">
</span><span id="line-12">
</span><span id="line-13"><span class="kn">from</span><span class="w"> </span><span class="nn">isek.util.logger</span><span class="w"> </span><span class="kn">import</span> <span class="n">logger</span> <span class="c1"># Assuming logger is configured</span>
</span><span id="line-14"><span class="kn">from</span><span class="w"> </span><span class="nn">isek.node.registry</span><span class="w"> </span><span class="kn">import</span> <span class="n">Registry</span> <span class="c1"># Assuming Registry is an ABC or base class</span>
</span><span id="line-15">
</span><span id="line-16"><span class="c1"># Type alias for node metadata</span>
</span><span id="line-17"><span class="n">NodeMetadata</span> <span class="o">=</span> <span class="n">Dict</span><span class="p">[</span><span class="nb">str</span><span class="p">,</span> <span class="nb">str</span><span class="p">]</span>
</span><span id="line-18"><span class="n">NodeInfo</span> <span class="o">=</span> <span class="n">Dict</span><span class="p">[</span><span class="nb">str</span><span class="p">,</span> <span class="n">Any</span><span class="p">]</span> <span class="c1"># More specific than just Dict[str, str] as port is int</span>
</span><span id="line-19">
<div class="viewcode-block" id="EtcdRegistry">
<a class="viewcode-back" href="../../../api/node.html#isek.node.EtcdRegistry">[docs]</a>
</span><span id="line-20"><span class="k">class</span><span class="w"> </span><span class="nc">EtcdRegistry</span><span class="p">(</span><span class="n">Registry</span><span class="p">):</span>
</span><span id="line-21"><span class="w">    </span><span class="sd">&quot;&quot;&quot;</span>
</span><span id="line-22"><span class="sd">    An implementation of the :class:`~isek.node.registry.Registry` interface</span>
</span><span id="line-23"><span class="sd">    that uses etcd as a distributed key-value store for service discovery.</span>
</span><span id="line-24">
</span><span id="line-25"><span class="sd">    Nodes register themselves with their connection information and metadata.</span>
</span><span id="line-26"><span class="sd">    The registry uses leases to automatically deregister nodes if they fail</span>
</span><span id="line-27"><span class="sd">    to refresh their lease, providing a degree of fault tolerance.</span>
</span><span id="line-28"><span class="sd">    Node information is signed to ensure integrity and authenticity, although</span>
</span><span id="line-29"><span class="sd">    the current signature verification logic in `__verify_signature` appears</span>
</span><span id="line-30"><span class="sd">    to verify a signature it just created, rather than a signature from a remote node.</span>
</span><span id="line-31"><span class="sd">    &quot;&quot;&quot;</span>
</span><span id="line-32">
</span><span id="line-33">    <span class="k">def</span><span class="w"> </span><span class="fm">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span>
</span><span id="line-34">                 <span class="n">host</span><span class="p">:</span> <span class="n">Optional</span><span class="p">[</span><span class="nb">str</span><span class="p">]</span> <span class="o">=</span> <span class="kc">None</span><span class="p">,</span>
</span><span id="line-35">                 <span class="n">port</span><span class="p">:</span> <span class="n">Optional</span><span class="p">[</span><span class="nb">int</span><span class="p">]</span> <span class="o">=</span> <span class="kc">None</span><span class="p">,</span>
</span><span id="line-36">                 <span class="n">parent_node_id</span><span class="p">:</span> <span class="nb">str</span> <span class="o">=</span> <span class="s2">&quot;root&quot;</span><span class="p">,</span> <span class="c1"># Made non-optional with default</span>
</span><span id="line-37">                 <span class="n">etcd_client</span><span class="p">:</span> <span class="n">Optional</span><span class="p">[</span><span class="n">etcd3</span><span class="o">.</span><span class="n">Etcd3Client</span><span class="p">]</span> <span class="o">=</span> <span class="kc">None</span><span class="p">,</span>
</span><span id="line-38">                 <span class="n">ttl</span><span class="p">:</span> <span class="nb">int</span> <span class="o">=</span> <span class="mi">30</span><span class="p">):</span>
</span><span id="line-39"><span class="w">        </span><span class="sd">&quot;&quot;&quot;</span>
</span><span id="line-40"><span class="sd">        Initializes the EtcdRegistry.</span>
</span><span id="line-41">
</span><span id="line-42"><span class="sd">        Connection to etcd can be established either by providing an existing</span>
</span><span id="line-43"><span class="sd">        `etcd_client` object or by specifying `host` and `port`.</span>
</span><span id="line-44">
</span><span id="line-45"><span class="sd">        :param host: The hostname or IP address of the etcd server.</span>
</span><span id="line-46"><span class="sd">                     Used if `etcd_client` is not provided.</span>
</span><span id="line-47"><span class="sd">        :type host: typing.Optional[str]</span>
</span><span id="line-48"><span class="sd">        :param port: The port number of the etcd server.</span>
</span><span id="line-49"><span class="sd">                     Used if `etcd_client` is not provided.</span>
</span><span id="line-50"><span class="sd">        :type port: typing.Optional[int]</span>
</span><span id="line-51"><span class="sd">        :param parent_node_id: The root path or prefix in etcd under which nodes</span>
</span><span id="line-52"><span class="sd">                               will be registered. Defaults to &quot;root&quot;.</span>
</span><span id="line-53"><span class="sd">        :type parent_node_id: str</span>
</span><span id="line-54"><span class="sd">        :param etcd_client: An optional pre-configured `etcd3.Etcd3Client` instance.</span>
</span><span id="line-55"><span class="sd">                            If provided, `host` and `port` are ignored.</span>
</span><span id="line-56"><span class="sd">        :type etcd_client: typing.Optional[etcd3.Etcd3Client]</span>
</span><span id="line-57"><span class="sd">        :param ttl: Time-to-live (in seconds) for node leases. Nodes must refresh</span>
</span><span id="line-58"><span class="sd">                    their lease within this period to remain registered. Defaults to 30.</span>
</span><span id="line-59"><span class="sd">        :type ttl: int</span>
</span><span id="line-60"><span class="sd">        :raises TypeError: If neither (`host` and `port`) nor `etcd_client` is provided.</span>
</span><span id="line-61"><span class="sd">        :raises ConnectionError: If the connection to the etcd server cannot be established.</span>
</span><span id="line-62"><span class="sd">        &quot;&quot;&quot;</span>
</span><span id="line-63">        <span class="k">if</span> <span class="n">host</span> <span class="ow">and</span> <span class="n">port</span> <span class="ow">and</span> <span class="n">etcd_client</span><span class="p">:</span>
</span><span id="line-64">            <span class="n">logger</span><span class="o">.</span><span class="n">warning</span><span class="p">(</span><span class="s2">&quot;Both &#39;host/port&#39; and &#39;etcd_client&#39; were provided. &quot;</span>
</span><span id="line-65">                           <span class="s2">&quot;The existing &#39;etcd_client&#39; will be used.&quot;</span><span class="p">)</span>
</span><span id="line-66">
</span><span id="line-67">        <span class="k">if</span> <span class="n">etcd_client</span><span class="p">:</span>
</span><span id="line-68">            <span class="bp">self</span><span class="o">.</span><span class="n">etcd_client</span><span class="p">:</span> <span class="n">etcd3</span><span class="o">.</span><span class="n">Etcd3Client</span> <span class="o">=</span> <span class="n">etcd_client</span>
</span><span id="line-69">        <span class="k">elif</span> <span class="n">host</span> <span class="ow">and</span> <span class="n">port</span><span class="p">:</span>
</span><span id="line-70">            <span class="bp">self</span><span class="o">.</span><span class="n">etcd_client</span> <span class="o">=</span> <span class="n">etcd3</span><span class="o">.</span><span class="n">client</span><span class="p">(</span><span class="n">host</span><span class="o">=</span><span class="n">host</span><span class="p">,</span> <span class="n">port</span><span class="o">=</span><span class="n">port</span><span class="p">)</span>
</span><span id="line-71">        <span class="k">else</span><span class="p">:</span>
</span><span id="line-72">            <span class="k">raise</span> <span class="ne">TypeError</span><span class="p">(</span><span class="s2">&quot;Either (&#39;host&#39; and &#39;port&#39;) or &#39;etcd_client&#39; must be provided to EtcdRegistry.&quot;</span><span class="p">)</span>
</span><span id="line-73">
</span><span id="line-74">        <span class="bp">self</span><span class="o">.</span><span class="n">parent_node_id</span><span class="p">:</span> <span class="nb">str</span> <span class="o">=</span> <span class="n">parent_node_id</span> <span class="c1"># Defaults to &quot;root&quot; if None was passed</span>
</span><span id="line-75">
</span><span id="line-76">        <span class="k">try</span><span class="p">:</span>
</span><span id="line-77">            <span class="c1"># Check etcd server status</span>
</span><span id="line-78">            <span class="n">status_check</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">etcd_client</span><span class="o">.</span><span class="n">status</span><span class="p">()</span>
</span><span id="line-79">            <span class="k">if</span> <span class="ow">not</span> <span class="n">status_check</span><span class="p">:</span> <span class="c1"># status() might return None or raise on failure</span>
</span><span id="line-80">                <span class="k">raise</span> <span class="ne">ConnectionError</span><span class="p">(</span><span class="s2">&quot;etcd client status check returned an unhealthy or falsy status.&quot;</span><span class="p">)</span>
</span><span id="line-81">            <span class="n">logger</span><span class="o">.</span><span class="n">info</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Successfully connected to etcd server. Version: </span><span class="si">{</span><span class="n">status_check</span><span class="o">.</span><span class="n">version</span><span class="si">}</span><span class="s2">&quot;</span><span class="p">)</span>
</span><span id="line-82">        <span class="k">except</span> <span class="ne">Exception</span> <span class="k">as</span> <span class="n">e</span><span class="p">:</span> <span class="c1"># Catch broader exceptions from etcd3.client or status()</span>
</span><span id="line-83">            <span class="k">raise</span> <span class="ne">ConnectionError</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Failed to connect to the etcd server or get status: </span><span class="si">{</span><span class="n">e</span><span class="si">}</span><span class="s2">&quot;</span><span class="p">)</span> <span class="kn">from</span><span class="w"> </span><span class="nn">e</span>
</span><span id="line-84">
</span><span id="line-85">        <span class="c1"># This signing key is for this registry instance to sign data it puts,</span>
</span><span id="line-86">        <span class="c1"># or for nodes this registry *manages* if it were creating their entries.</span>
</span><span id="line-87">        <span class="c1"># If nodes sign their own data, this SK would be for verifying their VKs,</span>
</span><span id="line-88">        <span class="c1"># or this registry would need its own identity for others to verify.</span>
</span><span id="line-89">        <span class="bp">self</span><span class="o">.</span><span class="n">sk</span><span class="p">:</span> <span class="n">SigningKey</span> <span class="o">=</span> <span class="n">SigningKey</span><span class="o">.</span><span class="n">generate</span><span class="p">(</span><span class="n">curve</span><span class="o">=</span><span class="n">NIST256p</span><span class="p">)</span>
</span><span id="line-90">        <span class="bp">self</span><span class="o">.</span><span class="n">vk_base64</span><span class="p">:</span> <span class="nb">str</span> <span class="o">=</span> <span class="n">base64</span><span class="o">.</span><span class="n">b64encode</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">sk</span><span class="o">.</span><span class="n">verifying_key</span><span class="o">.</span><span class="n">to_string</span><span class="p">())</span><span class="o">.</span><span class="n">decode</span><span class="p">(</span><span class="s1">&#39;utf-8&#39;</span><span class="p">)</span>
</span><span id="line-91">
</span><span id="line-92">
</span><span id="line-93">        <span class="bp">self</span><span class="o">.</span><span class="n">ttl</span><span class="p">:</span> <span class="nb">int</span> <span class="o">=</span> <span class="n">ttl</span>
</span><span id="line-94">        <span class="bp">self</span><span class="o">.</span><span class="n">leases</span><span class="p">:</span> <span class="n">Dict</span><span class="p">[</span><span class="nb">str</span><span class="p">,</span> <span class="n">etcd3</span><span class="o">.</span><span class="n">Lease</span><span class="p">]</span> <span class="o">=</span> <span class="p">{}</span> <span class="c1"># Stores lease objects per node_id</span>
</span><span id="line-95">
<div class="viewcode-block" id="EtcdRegistry.register_node">
<a class="viewcode-back" href="../../../api/node.html#isek.node.EtcdRegistry.register_node">[docs]</a>
</span><span id="line-96">    <span class="k">def</span><span class="w"> </span><span class="nf">register_node</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">node_id</span><span class="p">:</span> <span class="nb">str</span><span class="p">,</span> <span class="n">host</span><span class="p">:</span> <span class="nb">str</span><span class="p">,</span> <span class="n">port</span><span class="p">:</span> <span class="nb">int</span><span class="p">,</span> <span class="n">metadata</span><span class="p">:</span> <span class="n">Optional</span><span class="p">[</span><span class="n">NodeMetadata</span><span class="p">]</span> <span class="o">=</span> <span class="kc">None</span><span class="p">)</span> <span class="o">-&gt;</span> <span class="kc">None</span><span class="p">:</span>
</span><span id="line-97"><span class="w">        </span><span class="sd">&quot;&quot;&quot;</span>
</span><span id="line-98"><span class="sd">        Registers a node with the etcd service registry.</span>
</span><span id="line-99">
</span><span id="line-100"><span class="sd">        A lease is created for the node, and its information (including a public key</span>
</span><span id="line-101"><span class="sd">        derived from this registry&#39;s signing key) is stored in etcd. The node&#39;s</span>
</span><span id="line-102"><span class="sd">        information is signed by this registry instance.</span>
</span><span id="line-103">
</span><span id="line-104"><span class="sd">        .. warning::</span>
</span><span id="line-105"><span class="sd">            The public key stored (`vk_base64`) is derived from this `EtcdRegistry`</span>
</span><span id="line-106"><span class="sd">            instance&#39;s private key (`self.sk`). This means the registry is asserting</span>
</span><span id="line-107"><span class="sd">            the identity of the node by signing its details. If nodes are meant to</span>
</span><span id="line-108"><span class="sd">            have their own identities, they should generate their own key pairs and</span>
</span><span id="line-109"><span class="sd">            provide their public key for registration.</span>
</span><span id="line-110">
</span><span id="line-111"><span class="sd">        :param node_id: The unique identifier for the node.</span>
</span><span id="line-112"><span class="sd">        :type node_id: str</span>
</span><span id="line-113"><span class="sd">        :param host: The hostname or IP address where the node can be reached.</span>
</span><span id="line-114"><span class="sd">        :type host: str</span>
</span><span id="line-115"><span class="sd">        :param port: The port number on which the node is listening.</span>
</span><span id="line-116"><span class="sd">        :type port: int</span>
</span><span id="line-117"><span class="sd">        :param metadata: Optional dictionary of key-value pairs providing additional</span>
</span><span id="line-118"><span class="sd">                         information about the node. Defaults to an empty dictionary.</span>
</span><span id="line-119"><span class="sd">        :type metadata: typing.Optional[NodeMetadata]</span>
</span><span id="line-120"><span class="sd">        &quot;&quot;&quot;</span>
</span><span id="line-121">        <span class="c1"># The public key stored is this registry&#39;s public key, used to sign the node_info.</span>
</span><span id="line-122">        <span class="c1"># This implies the registry is attesting to the node_info.</span>
</span><span id="line-123">        <span class="n">node_info</span><span class="p">:</span> <span class="n">NodeInfo</span> <span class="o">=</span> <span class="p">{</span>
</span><span id="line-124">            <span class="s2">&quot;node_id&quot;</span><span class="p">:</span> <span class="n">node_id</span><span class="p">,</span>
</span><span id="line-125">            <span class="s2">&quot;host&quot;</span><span class="p">:</span> <span class="n">host</span><span class="p">,</span>
</span><span id="line-126">            <span class="s2">&quot;port&quot;</span><span class="p">:</span> <span class="n">port</span><span class="p">,</span>
</span><span id="line-127">            <span class="s2">&quot;public_key&quot;</span><span class="p">:</span> <span class="bp">self</span><span class="o">.</span><span class="n">vk_base64</span><span class="p">,</span> <span class="c1"># This registry&#39;s public key</span>
</span><span id="line-128">            <span class="s2">&quot;metadata&quot;</span><span class="p">:</span> <span class="n">metadata</span> <span class="ow">or</span> <span class="p">{}</span>
</span><span id="line-129">        <span class="p">}</span>
</span><span id="line-130">
</span><span id="line-131">        <span class="c1"># Sign the node_info (deterministically for consistency if needed)</span>
</span><span id="line-132">        <span class="n">node_info_json_bytes</span><span class="p">:</span> <span class="nb">bytes</span> <span class="o">=</span> <span class="n">json</span><span class="o">.</span><span class="n">dumps</span><span class="p">(</span><span class="n">node_info</span><span class="p">,</span> <span class="n">sort_keys</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span><span class="o">.</span><span class="n">encode</span><span class="p">(</span><span class="s2">&quot;utf-8&quot;</span><span class="p">)</span>
</span><span id="line-133">        <span class="c1"># Using sign_deterministic for consistent signatures if the input is identical.</span>
</span><span id="line-134">        <span class="c1"># Standard sign() might produce different valid signatures for the same input.</span>
</span><span id="line-135">        <span class="n">signature_bytes</span><span class="p">:</span> <span class="nb">bytes</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">sk</span><span class="o">.</span><span class="n">sign_deterministic</span><span class="p">(</span><span class="n">node_info_json_bytes</span><span class="p">,</span> <span class="n">sigencode</span><span class="o">=</span><span class="n">sigencode_der</span><span class="p">)</span>
</span><span id="line-136">        <span class="n">signature_base64</span><span class="p">:</span> <span class="nb">str</span> <span class="o">=</span> <span class="n">base64</span><span class="o">.</span><span class="n">b64encode</span><span class="p">(</span><span class="n">signature_bytes</span><span class="p">)</span><span class="o">.</span><span class="n">decode</span><span class="p">(</span><span class="s2">&quot;utf-8&quot;</span><span class="p">)</span>
</span><span id="line-137">
</span><span id="line-138">        <span class="n">node_entry</span><span class="p">:</span> <span class="n">Dict</span><span class="p">[</span><span class="nb">str</span><span class="p">,</span> <span class="n">Any</span><span class="p">]</span> <span class="o">=</span> <span class="p">{</span>
</span><span id="line-139">            <span class="s2">&quot;node_info&quot;</span><span class="p">:</span> <span class="n">node_info</span><span class="p">,</span>
</span><span id="line-140">            <span class="s2">&quot;signature&quot;</span><span class="p">:</span> <span class="n">signature_base64</span> <span class="c1"># Signature created by this registry instance</span>
</span><span id="line-141">        <span class="p">}</span>
</span><span id="line-142">
</span><span id="line-143">        <span class="k">try</span><span class="p">:</span>
</span><span id="line-144">            <span class="n">lease</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">etcd_client</span><span class="o">.</span><span class="n">lease</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">ttl</span><span class="p">)</span>
</span><span id="line-145">            <span class="bp">self</span><span class="o">.</span><span class="n">leases</span><span class="p">[</span><span class="n">node_id</span><span class="p">]</span> <span class="o">=</span> <span class="n">lease</span> <span class="c1"># Store lease to manage it</span>
</span><span id="line-146">
</span><span id="line-147">            <span class="n">key</span><span class="p">:</span> <span class="nb">str</span> <span class="o">=</span> <span class="sa">f</span><span class="s2">&quot;/</span><span class="si">{</span><span class="bp">self</span><span class="o">.</span><span class="n">parent_node_id</span><span class="si">}</span><span class="s2">/</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&quot;</span>
</span><span id="line-148">            <span class="bp">self</span><span class="o">.</span><span class="n">etcd_client</span><span class="o">.</span><span class="n">put</span><span class="p">(</span><span class="n">key</span><span class="p">,</span> <span class="n">json</span><span class="o">.</span><span class="n">dumps</span><span class="p">(</span><span class="n">node_entry</span><span class="p">),</span> <span class="n">lease</span><span class="o">=</span><span class="n">lease</span><span class="p">)</span>
</span><span id="line-149">
</span><span id="line-150">            <span class="n">logger</span><span class="o">.</span><span class="n">info</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Node &#39;</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&#39; registered successfully under key &#39;</span><span class="si">{</span><span class="n">key</span><span class="si">}</span><span class="s2">&#39; with TTL </span><span class="si">{</span><span class="bp">self</span><span class="o">.</span><span class="n">ttl</span><span class="si">}</span><span class="s2">s. &quot;</span>
</span><span id="line-151">                        <span class="sa">f</span><span class="s2">&quot;Info: </span><span class="si">{</span><span class="n">node_info</span><span class="si">}</span><span class="s2">&quot;</span><span class="p">)</span>
</span><span id="line-152">        <span class="k">except</span> <span class="ne">Exception</span> <span class="k">as</span> <span class="n">e</span><span class="p">:</span>
</span><span id="line-153">            <span class="n">logger</span><span class="o">.</span><span class="n">error</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Failed to register node &#39;</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&#39;: </span><span class="si">{</span><span class="n">e</span><span class="si">}</span><span class="s2">&quot;</span><span class="p">,</span> <span class="n">exc_info</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span>
</span><span id="line-154">            <span class="c1"># Optionally revoke lease if created but put failed</span>
</span><span id="line-155">            <span class="k">if</span> <span class="n">node_id</span> <span class="ow">in</span> <span class="bp">self</span><span class="o">.</span><span class="n">leases</span> <span class="ow">and</span> <span class="s1">&#39;lease&#39;</span> <span class="ow">in</span> <span class="nb">locals</span><span class="p">()</span> <span class="ow">and</span> <span class="n">lease</span> <span class="ow">is</span> <span class="ow">not</span> <span class="kc">None</span><span class="p">:</span>
</span><span id="line-156">                 <span class="k">try</span><span class="p">:</span>
</span><span id="line-157">                    <span class="n">lease</span><span class="o">.</span><span class="n">revoke</span><span class="p">()</span>
</span><span id="line-158">                 <span class="k">except</span> <span class="ne">Exception</span> <span class="k">as</span> <span class="n">rev_e</span><span class="p">:</span>
</span><span id="line-159">                    <span class="n">logger</span><span class="o">.</span><span class="n">error</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Failed to revoke lease for &#39;</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&#39; during registration error cleanup: </span><span class="si">{</span><span class="n">rev_e</span><span class="si">}</span><span class="s2">&quot;</span><span class="p">)</span>
</span><span id="line-160">                 <span class="k">del</span> <span class="bp">self</span><span class="o">.</span><span class="n">leases</span><span class="p">[</span><span class="n">node_id</span><span class="p">]</span>
</span><span id="line-161">            <span class="k">raise</span> <span class="c1"># Re-raise the original exception</span></div>

</span><span id="line-162">
<div class="viewcode-block" id="EtcdRegistry.lease_refresh">
<a class="viewcode-back" href="../../../api/node.html#isek.node.EtcdRegistry.lease_refresh">[docs]</a>
</span><span id="line-163">    <span class="k">def</span><span class="w"> </span><span class="nf">lease_refresh</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">node_id</span><span class="p">:</span> <span class="nb">str</span><span class="p">)</span> <span class="o">-&gt;</span> <span class="kc">None</span><span class="p">:</span>
</span><span id="line-164"><span class="w">        </span><span class="sd">&quot;&quot;&quot;</span>
</span><span id="line-165"><span class="sd">        Refreshes the lease for a registered node.</span>
</span><span id="line-166">
</span><span id="line-167"><span class="sd">        This method should be called periodically by the node (or on its behalf)</span>
</span><span id="line-168"><span class="sd">        to prevent its registration from expiring.</span>
</span><span id="line-169">
</span><span id="line-170"><span class="sd">        .. note::</span>
</span><span id="line-171"><span class="sd">            The current `__verify_signature` call within this method appears to</span>
</span><span id="line-172"><span class="sd">            re-verify a signature generated by this same registry instance, which might</span>
</span><span id="line-173"><span class="sd">            not be the intended security check if nodes have their own identities.</span>
</span><span id="line-174"><span class="sd">            If the goal is for the node to prove its identity to refresh, it would</span>
</span><span id="line-175"><span class="sd">            need to provide a signature that this registry verifies against the node&#39;s</span>
</span><span id="line-176"><span class="sd">            stored public key.</span>
</span><span id="line-177">
</span><span id="line-178"><span class="sd">        :param node_id: The ID of the node whose lease needs to be refreshed.</span>
</span><span id="line-179"><span class="sd">        :type node_id: str</span>
</span><span id="line-180"><span class="sd">        :raises KeyError: If the node_id is not found in the local lease cache.</span>
</span><span id="line-181"><span class="sd">        :raises ValueError: If signature verification fails (as per current `__verify_signature` logic).</span>
</span><span id="line-182"><span class="sd">        :raises Exception: If the etcd lease refresh operation fails.</span>
</span><span id="line-183"><span class="sd">        &quot;&quot;&quot;</span>
</span><span id="line-184">        <span class="k">if</span> <span class="n">node_id</span> <span class="ow">not</span> <span class="ow">in</span> <span class="bp">self</span><span class="o">.</span><span class="n">leases</span><span class="p">:</span>
</span><span id="line-185">            <span class="n">logger</span><span class="o">.</span><span class="n">warning</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Lease refresh attempted for node &#39;</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&#39; which has no active lease &quot;</span>
</span><span id="line-186">                           <span class="s2">&quot;cached in this registry instance. The node might need to re-register.&quot;</span><span class="p">)</span>
</span><span id="line-187">            <span class="c1"># Or raise KeyError(&quot;Node not found in local lease cache or needs to re-register.&quot;)</span>
</span><span id="line-188">            <span class="k">return</span> <span class="c1"># Or re-register, or raise. Current behavior is to log and return.</span>
</span><span id="line-189">
</span><span id="line-190">        <span class="k">try</span><span class="p">:</span>
</span><span id="line-191">            <span class="c1"># The signature verification here checks the signature made by *this* registry instance.</span>
</span><span id="line-192">            <span class="c1"># This confirms the data in etcd hasn&#39;t been tampered with in a way that invalidates</span>
</span><span id="line-193">            <span class="c1"># *this registry&#39;s* signature. It doesn&#39;t verify the node&#39;s identity if the node</span>
</span><span id="line-194">            <span class="c1"># was supposed to sign something.</span>
</span><span id="line-195">            <span class="bp">self</span><span class="o">.</span><span class="n">__verify_signature</span><span class="p">(</span><span class="n">node_id</span><span class="p">)</span> <span class="c1"># Verifies data integrity based on registry&#39;s key</span>
</span><span id="line-196">
</span><span id="line-197">            <span class="c1"># Refresh the lease</span>
</span><span id="line-198">            <span class="n">refresh_responses</span> <span class="o">=</span> <span class="nb">list</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">leases</span><span class="p">[</span><span class="n">node_id</span><span class="p">]</span><span class="o">.</span><span class="n">refresh</span><span class="p">())</span> <span class="c1"># refresh() is a generator</span>
</span><span id="line-199">            <span class="k">if</span> <span class="ow">not</span> <span class="n">refresh_responses</span> <span class="ow">or</span> <span class="n">refresh_responses</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span><span class="o">.</span><span class="n">ttl</span> <span class="o">&lt;=</span> <span class="mi">0</span><span class="p">:</span> <span class="c1"># Check if refresh was successful</span>
</span><span id="line-200">                <span class="n">logger</span><span class="o">.</span><span class="n">warning</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Lease refresh for node &#39;</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&#39; might have failed or TTL is 0. Responses: </span><span class="si">{</span><span class="n">refresh_responses</span><span class="si">}</span><span class="s2">&quot;</span><span class="p">)</span>
</span><span id="line-201">                <span class="c1"># Potentially attempt to re-establish lease or re-register</span>
</span><span id="line-202">            <span class="k">else</span><span class="p">:</span>
</span><span id="line-203">                <span class="n">logger</span><span class="o">.</span><span class="n">debug</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Lease successfully refreshed for node &#39;</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&#39;. New TTL: </span><span class="si">{</span><span class="n">refresh_responses</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span><span class="o">.</span><span class="n">ttl</span><span class="si">}</span><span class="s2">s&quot;</span><span class="p">)</span>
</span><span id="line-204">
</span><span id="line-205">        <span class="k">except</span> <span class="n">BadSignatureError</span> <span class="k">as</span> <span class="n">e</span><span class="p">:</span> <span class="c1"># More specific error from ecdsa</span>
</span><span id="line-206">            <span class="n">logger</span><span class="o">.</span><span class="n">error</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Lease renewal for node &#39;</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&#39; failed due to signature verification error: </span><span class="si">{</span><span class="n">e</span><span class="si">}</span><span class="s2">&quot;</span><span class="p">,</span> <span class="n">exc_info</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span>
</span><span id="line-207">            <span class="c1"># Potentially deregister or mark node as suspect</span>
</span><span id="line-208">            <span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Signature verification failed for node &#39;</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&#39; during lease refresh.&quot;</span><span class="p">)</span> <span class="kn">from</span><span class="w"> </span><span class="nn">e</span>
</span><span id="line-209">        <span class="k">except</span> <span class="ne">Exception</span> <span class="k">as</span> <span class="n">e</span><span class="p">:</span>
</span><span id="line-210">            <span class="n">logger</span><span class="o">.</span><span class="n">error</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Lease renewal failed for node &#39;</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&#39;: </span><span class="si">{</span><span class="n">e</span><span class="si">}</span><span class="s2">&quot;</span><span class="p">,</span> <span class="n">exc_info</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span>
</span><span id="line-211">            <span class="c1"># Re-raise to indicate failure to the caller</span>
</span><span id="line-212">            <span class="k">raise</span></div>

</span><span id="line-213">
<div class="viewcode-block" id="EtcdRegistry.get_available_nodes">
<a class="viewcode-back" href="../../../api/node.html#isek.node.EtcdRegistry.get_available_nodes">[docs]</a>
</span><span id="line-214">    <span class="k">def</span><span class="w"> </span><span class="nf">get_available_nodes</span><span class="p">(</span><span class="bp">self</span><span class="p">)</span> <span class="o">-&gt;</span> <span class="n">Dict</span><span class="p">[</span><span class="nb">str</span><span class="p">,</span> <span class="n">NodeInfo</span><span class="p">]:</span>
</span><span id="line-215"><span class="w">        </span><span class="sd">&quot;&quot;&quot;</span>
</span><span id="line-216"><span class="sd">        Retrieves information about all currently registered and available nodes.</span>
</span><span id="line-217">
</span><span id="line-218"><span class="sd">        It fetches all entries under the configured `parent_node_id` prefix in etcd.</span>
</span><span id="line-219">
</span><span id="line-220"><span class="sd">        :return: A dictionary where keys are node IDs and values are dictionaries</span>
</span><span id="line-221"><span class="sd">                 containing the &#39;node_info&#39; (host, port, metadata, public_key)</span>
</span><span id="line-222"><span class="sd">                 for each available node.</span>
</span><span id="line-223"><span class="sd">        :rtype: typing.Dict[str, NodeInfo]</span>
</span><span id="line-224"><span class="sd">        &quot;&quot;&quot;</span>
</span><span id="line-225">        <span class="n">nodes</span><span class="p">:</span> <span class="n">Dict</span><span class="p">[</span><span class="nb">str</span><span class="p">,</span> <span class="n">NodeInfo</span><span class="p">]</span> <span class="o">=</span> <span class="p">{}</span>
</span><span id="line-226">        <span class="k">try</span><span class="p">:</span>
</span><span id="line-227">            <span class="n">key_prefix</span> <span class="o">=</span> <span class="sa">f</span><span class="s2">&quot;/</span><span class="si">{</span><span class="bp">self</span><span class="o">.</span><span class="n">parent_node_id</span><span class="si">}</span><span class="s2">/&quot;</span>
</span><span id="line-228">            <span class="k">for</span> <span class="n">value_bytes</span><span class="p">,</span> <span class="n">metadata_obj</span> <span class="ow">in</span> <span class="bp">self</span><span class="o">.</span><span class="n">etcd_client</span><span class="o">.</span><span class="n">get_prefix</span><span class="p">(</span><span class="n">key_prefix</span><span class="p">):</span>
</span><span id="line-229">                <span class="n">node_id_from_key</span> <span class="o">=</span> <span class="n">metadata_obj</span><span class="o">.</span><span class="n">key</span><span class="o">.</span><span class="n">decode</span><span class="p">(</span><span class="s2">&quot;utf-8&quot;</span><span class="p">)</span><span class="o">.</span><span class="n">split</span><span class="p">(</span><span class="n">key_prefix</span><span class="p">)[</span><span class="o">-</span><span class="mi">1</span><span class="p">]</span>
</span><span id="line-230">                <span class="k">try</span><span class="p">:</span>
</span><span id="line-231">                    <span class="n">node_entry</span> <span class="o">=</span> <span class="n">json</span><span class="o">.</span><span class="n">loads</span><span class="p">(</span><span class="n">value_bytes</span><span class="o">.</span><span class="n">decode</span><span class="p">(</span><span class="s2">&quot;utf-8&quot;</span><span class="p">))</span>
</span><span id="line-232">                    <span class="k">if</span> <span class="s1">&#39;node_info&#39;</span> <span class="ow">in</span> <span class="n">node_entry</span><span class="p">:</span>
</span><span id="line-233">                        <span class="n">nodes</span><span class="p">[</span><span class="n">node_id_from_key</span><span class="p">]</span> <span class="o">=</span> <span class="n">node_entry</span><span class="p">[</span><span class="s1">&#39;node_info&#39;</span><span class="p">]</span>
</span><span id="line-234">                    <span class="k">else</span><span class="p">:</span>
</span><span id="line-235">                        <span class="n">logger</span><span class="o">.</span><span class="n">warning</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Node entry for &#39;</span><span class="si">{</span><span class="n">node_id_from_key</span><span class="si">}</span><span class="s2">&#39; is missing &#39;node_info&#39; field. Entry: </span><span class="si">{</span><span class="n">node_entry</span><span class="si">}</span><span class="s2">&quot;</span><span class="p">)</span>
</span><span id="line-236">                <span class="k">except</span> <span class="n">json</span><span class="o">.</span><span class="n">JSONDecodeError</span> <span class="k">as</span> <span class="n">e</span><span class="p">:</span>
</span><span id="line-237">                    <span class="n">logger</span><span class="o">.</span><span class="n">error</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Error decoding JSON for node &#39;</span><span class="si">{</span><span class="n">node_id_from_key</span><span class="si">}</span><span class="s2">&#39;: </span><span class="si">{</span><span class="n">e</span><span class="si">}</span><span class="s2">. Value: &#39;</span><span class="si">{</span><span class="n">value_bytes</span><span class="p">[:</span><span class="mi">100</span><span class="p">]</span><span class="si">}</span><span class="s2">...&#39;&quot;</span><span class="p">)</span>
</span><span id="line-238">                <span class="k">except</span> <span class="ne">Exception</span> <span class="k">as</span> <span class="n">e</span><span class="p">:</span> <span class="c1"># Catch other potential errors during processing</span>
</span><span id="line-239">                    <span class="n">logger</span><span class="o">.</span><span class="n">error</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Unexpected error processing node entry for &#39;</span><span class="si">{</span><span class="n">node_id_from_key</span><span class="si">}</span><span class="s2">&#39;: </span><span class="si">{</span><span class="n">e</span><span class="si">}</span><span class="s2">&quot;</span><span class="p">,</span> <span class="n">exc_info</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span>
</span><span id="line-240">        <span class="k">except</span> <span class="ne">Exception</span> <span class="k">as</span> <span class="n">e</span><span class="p">:</span>
</span><span id="line-241">            <span class="n">logger</span><span class="o">.</span><span class="n">error</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Failed to get available nodes from etcd prefix &#39;</span><span class="si">{</span><span class="n">key_prefix</span><span class="si">}</span><span class="s2">&#39;: </span><span class="si">{</span><span class="n">e</span><span class="si">}</span><span class="s2">&quot;</span><span class="p">,</span> <span class="n">exc_info</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span>
</span><span id="line-242">            <span class="c1"># Depending on requirements, could return empty dict or raise</span>
</span><span id="line-243">        <span class="k">return</span> <span class="n">nodes</span></div>

</span><span id="line-244">
<div class="viewcode-block" id="EtcdRegistry.deregister_node">
<a class="viewcode-back" href="../../../api/node.html#isek.node.EtcdRegistry.deregister_node">[docs]</a>
</span><span id="line-245">    <span class="k">def</span><span class="w"> </span><span class="nf">deregister_node</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">node_id</span><span class="p">:</span> <span class="nb">str</span><span class="p">)</span> <span class="o">-&gt;</span> <span class="kc">None</span><span class="p">:</span>
</span><span id="line-246"><span class="w">        </span><span class="sd">&quot;&quot;&quot;</span>
</span><span id="line-247"><span class="sd">        Deregisters a node from the etcd service registry.</span>
</span><span id="line-248">
</span><span id="line-249"><span class="sd">        This involves deleting the node&#39;s entry from etcd and revoking its lease.</span>
</span><span id="line-250">
</span><span id="line-251"><span class="sd">        .. note::</span>
</span><span id="line-252"><span class="sd">            Similar to `lease_refresh`, the `__verify_signature` call here checks</span>
</span><span id="line-253"><span class="sd">            the integrity of the data based on this registry&#39;s signature.</span>
</span><span id="line-254">
</span><span id="line-255"><span class="sd">        :param node_id: The ID of the node to deregister.</span>
</span><span id="line-256"><span class="sd">        :type node_id: str</span>
</span><span id="line-257"><span class="sd">        :raises ValueError: If the node is not found or signature verification fails.</span>
</span><span id="line-258"><span class="sd">        :raises Exception: If etcd operations (delete, lease revoke) fail.</span>
</span><span id="line-259"><span class="sd">        &quot;&quot;&quot;</span>
</span><span id="line-260">        <span class="n">key</span><span class="p">:</span> <span class="nb">str</span> <span class="o">=</span> <span class="sa">f</span><span class="s2">&quot;/</span><span class="si">{</span><span class="bp">self</span><span class="o">.</span><span class="n">parent_node_id</span><span class="si">}</span><span class="s2">/</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&quot;</span>
</span><span id="line-261">        <span class="k">try</span><span class="p">:</span>
</span><span id="line-262">            <span class="c1"># Verify signature before deleting to ensure we are acting on valid data.</span>
</span><span id="line-263">            <span class="bp">self</span><span class="o">.</span><span class="n">__verify_signature</span><span class="p">(</span><span class="n">node_id</span><span class="p">)</span>
</span><span id="line-264">
</span><span id="line-265">            <span class="n">deleted_count</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">etcd_client</span><span class="o">.</span><span class="n">delete</span><span class="p">(</span><span class="n">key</span><span class="p">)</span>
</span><span id="line-266">            <span class="k">if</span> <span class="n">deleted_count</span> <span class="o">==</span> <span class="mi">0</span><span class="p">:</span> <span class="c1"># or delete returns False if not found</span>
</span><span id="line-267">                <span class="n">logger</span><span class="o">.</span><span class="n">warning</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Attempted to deregister node &#39;</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&#39; (key: &#39;</span><span class="si">{</span><span class="n">key</span><span class="si">}</span><span class="s2">&#39;), but it was not found in etcd.&quot;</span><span class="p">)</span>
</span><span id="line-268">                <span class="c1"># Still try to revoke local lease if it exists</span>
</span><span id="line-269">            <span class="k">else</span><span class="p">:</span>
</span><span id="line-270">                <span class="n">logger</span><span class="o">.</span><span class="n">info</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Node &#39;</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&#39; (key: &#39;</span><span class="si">{</span><span class="n">key</span><span class="si">}</span><span class="s2">&#39;) deleted from etcd.&quot;</span><span class="p">)</span>
</span><span id="line-271">
</span><span id="line-272">            <span class="c1"># Revoke and remove local lease cache</span>
</span><span id="line-273">            <span class="k">if</span> <span class="n">node_id</span> <span class="ow">in</span> <span class="bp">self</span><span class="o">.</span><span class="n">leases</span><span class="p">:</span>
</span><span id="line-274">                <span class="k">try</span><span class="p">:</span>
</span><span id="line-275">                    <span class="bp">self</span><span class="o">.</span><span class="n">leases</span><span class="p">[</span><span class="n">node_id</span><span class="p">]</span><span class="o">.</span><span class="n">revoke</span><span class="p">()</span>
</span><span id="line-276">                    <span class="n">logger</span><span class="o">.</span><span class="n">info</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Lease for node &#39;</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&#39; revoked.&quot;</span><span class="p">)</span>
</span><span id="line-277">                <span class="k">except</span> <span class="ne">Exception</span> <span class="k">as</span> <span class="n">e_lease</span><span class="p">:</span> <span class="c1"># etcd3 may raise errors if lease doesn&#39;t exist server-side</span>
</span><span id="line-278">                    <span class="n">logger</span><span class="o">.</span><span class="n">warning</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Error revoking lease for node &#39;</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&#39;: </span><span class="si">{</span><span class="n">e_lease</span><span class="si">}</span><span class="s2">. It might have already expired or been revoked.&quot;</span><span class="p">)</span>
</span><span id="line-279">                <span class="k">finally</span><span class="p">:</span>
</span><span id="line-280">                    <span class="k">del</span> <span class="bp">self</span><span class="o">.</span><span class="n">leases</span><span class="p">[</span><span class="n">node_id</span><span class="p">]</span>
</span><span id="line-281">            <span class="k">else</span><span class="p">:</span>
</span><span id="line-282">                <span class="n">logger</span><span class="o">.</span><span class="n">info</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;No local lease found for node &#39;</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&#39; to revoke during deregistration.&quot;</span><span class="p">)</span>
</span><span id="line-283">
</span><span id="line-284">        <span class="k">except</span> <span class="ne">ValueError</span> <span class="k">as</span> <span class="n">e</span><span class="p">:</span> <span class="c1"># From __verify_signature or if node not found in verification</span>
</span><span id="line-285">            <span class="n">logger</span><span class="o">.</span><span class="n">error</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Failed to deregister node &#39;</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&#39; due to an error: </span><span class="si">{</span><span class="n">e</span><span class="si">}</span><span class="s2">&quot;</span><span class="p">,</span> <span class="n">exc_info</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span>
</span><span id="line-286">            <span class="k">raise</span>
</span><span id="line-287">        <span class="k">except</span> <span class="ne">Exception</span> <span class="k">as</span> <span class="n">e</span><span class="p">:</span>
</span><span id="line-288">            <span class="n">logger</span><span class="o">.</span><span class="n">error</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;An unexpected error occurred while deregistering node &#39;</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&#39;: </span><span class="si">{</span><span class="n">e</span><span class="si">}</span><span class="s2">&quot;</span><span class="p">,</span> <span class="n">exc_info</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span>
</span><span id="line-289">            <span class="k">raise</span></div>

</span><span id="line-290">
</span><span id="line-291">    <span class="k">def</span><span class="w"> </span><span class="nf">__verify_signature</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">node_id</span><span class="p">:</span> <span class="nb">str</span><span class="p">)</span> <span class="o">-&gt;</span> <span class="kc">None</span><span class="p">:</span>
</span><span id="line-292"><span class="w">        </span><span class="sd">&quot;&quot;&quot;</span>
</span><span id="line-293"><span class="sd">        Verifies the signature of a node&#39;s entry stored in etcd.</span>
</span><span id="line-294">
</span><span id="line-295"><span class="sd">        This method fetches the node&#39;s entry, extracts its `node_info` and `signature`,</span>
</span><span id="line-296"><span class="sd">        and verifies that the signature matches one calculated using this registry&#39;s</span>
</span><span id="line-297"><span class="sd">        private key (`self.sk`) over the `node_info`. It also verifies the signature</span>
</span><span id="line-298"><span class="sd">        against the public key stored within the `node_info` itself (which is this</span>
</span><span id="line-299"><span class="sd">        registry&#39;s public key).</span>
</span><span id="line-300">
</span><span id="line-301"><span class="sd">        This effectively checks:</span>
</span><span id="line-302"><span class="sd">        1. That the `node_info` has not been tampered with since this registry instance signed it.</span>
</span><span id="line-303"><span class="sd">        2. That the public key stored in `node_info` corresponds to the private key that</span>
</span><span id="line-304"><span class="sd">           created the signature (i.e., `self.sk`).</span>
</span><span id="line-305">
</span><span id="line-306"><span class="sd">        .. warning::</span>
</span><span id="line-307"><span class="sd">            This method verifies a signature made by *this registry instance&#39;s* private key.</span>
</span><span id="line-308"><span class="sd">            It does *not* verify a signature made by the registered node itself using its own</span>
</span><span id="line-309"><span class="sd">            private key, unless the node&#39;s public key was explicitly registered and used here.</span>
</span><span id="line-310"><span class="sd">            The current implementation uses `self.sk` to *re-calculate* the expected signature.</span>
</span><span id="line-311">
</span><span id="line-312"><span class="sd">        :param node_id: The ID of the node whose signature is to be verified.</span>
</span><span id="line-313"><span class="sd">        :type node_id: str</span>
</span><span id="line-314"><span class="sd">        :raises ValueError: If the node is not found in etcd, if signature verification fails,</span>
</span><span id="line-315"><span class="sd">                            or if the public key verification fails.</span>
</span><span id="line-316"><span class="sd">        :raises BadSignatureError: If `vk.verify` fails due to a malformed or incorrect signature.</span>
</span><span id="line-317"><span class="sd">        &quot;&quot;&quot;</span>
</span><span id="line-318">        <span class="n">key</span> <span class="o">=</span> <span class="sa">f</span><span class="s2">&quot;/</span><span class="si">{</span><span class="bp">self</span><span class="o">.</span><span class="n">parent_node_id</span><span class="si">}</span><span class="s2">/</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&quot;</span>
</span><span id="line-319">        <span class="n">value_bytes</span><span class="p">,</span> <span class="n">_</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">etcd_client</span><span class="o">.</span><span class="n">get</span><span class="p">(</span><span class="n">key</span><span class="p">)</span> <span class="c1"># get() returns (value, metadata) or (None, None)</span>
</span><span id="line-320">
</span><span id="line-321">        <span class="k">if</span> <span class="n">value_bytes</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span>
</span><span id="line-322">            <span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Node &#39;</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&#39; (key: &#39;</span><span class="si">{</span><span class="n">key</span><span class="si">}</span><span class="s2">&#39;) not found in etcd for signature verification.&quot;</span><span class="p">)</span>
</span><span id="line-323">
</span><span id="line-324">        <span class="k">try</span><span class="p">:</span>
</span><span id="line-325">            <span class="n">node_entry</span> <span class="o">=</span> <span class="n">json</span><span class="o">.</span><span class="n">loads</span><span class="p">(</span><span class="n">value_bytes</span><span class="o">.</span><span class="n">decode</span><span class="p">(</span><span class="s2">&quot;utf-8&quot;</span><span class="p">))</span>
</span><span id="line-326">        <span class="k">except</span> <span class="n">json</span><span class="o">.</span><span class="n">JSONDecodeError</span> <span class="k">as</span> <span class="n">e</span><span class="p">:</span>
</span><span id="line-327">            <span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Failed to decode JSON for node &#39;</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&#39; (key: &#39;</span><span class="si">{</span><span class="n">key</span><span class="si">}</span><span class="s2">&#39;): </span><span class="si">{</span><span class="n">e</span><span class="si">}</span><span class="s2">&quot;</span><span class="p">)</span> <span class="kn">from</span><span class="w"> </span><span class="nn">e</span>
</span><span id="line-328">
</span><span id="line-329">
</span><span id="line-330">        <span class="k">if</span> <span class="s2">&quot;node_info&quot;</span> <span class="ow">not</span> <span class="ow">in</span> <span class="n">node_entry</span> <span class="ow">or</span> <span class="s2">&quot;signature&quot;</span> <span class="ow">not</span> <span class="ow">in</span> <span class="n">node_entry</span><span class="p">:</span>
</span><span id="line-331">            <span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Node entry for &#39;</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&#39; is malformed (missing &#39;node_info&#39; or &#39;signature&#39;).&quot;</span><span class="p">)</span>
</span><span id="line-332">
</span><span id="line-333">        <span class="n">node_info</span><span class="p">:</span> <span class="n">NodeInfo</span> <span class="o">=</span> <span class="n">node_entry</span><span class="p">[</span><span class="s2">&quot;node_info&quot;</span><span class="p">]</span>
</span><span id="line-334">        <span class="n">stored_signature_base64</span><span class="p">:</span> <span class="nb">str</span> <span class="o">=</span> <span class="n">node_entry</span><span class="p">[</span><span class="s2">&quot;signature&quot;</span><span class="p">]</span>
</span><span id="line-335">
</span><span id="line-336">        <span class="k">if</span> <span class="s2">&quot;public_key&quot;</span> <span class="ow">not</span> <span class="ow">in</span> <span class="n">node_info</span><span class="p">:</span>
</span><span id="line-337">            <span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Node info for &#39;</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&#39; is missing &#39;public_key&#39;.&quot;</span><span class="p">)</span>
</span><span id="line-338">
</span><span id="line-339">        <span class="c1"># This is the public key *this registry* stored, derived from self.sk</span>
</span><span id="line-340">        <span class="n">vk_from_storage_base64</span><span class="p">:</span> <span class="nb">str</span> <span class="o">=</span> <span class="n">node_info</span><span class="p">[</span><span class="s2">&quot;public_key&quot;</span><span class="p">]</span>
</span><span id="line-341">        <span class="k">try</span><span class="p">:</span>
</span><span id="line-342">            <span class="n">vk_bytes_from_storage</span><span class="p">:</span> <span class="nb">bytes</span> <span class="o">=</span> <span class="n">base64</span><span class="o">.</span><span class="n">b64decode</span><span class="p">(</span><span class="n">vk_from_storage_base64</span><span class="p">)</span>
</span><span id="line-343">            <span class="n">vk_from_storage</span><span class="p">:</span> <span class="n">VerifyingKey</span> <span class="o">=</span> <span class="n">VerifyingKey</span><span class="o">.</span><span class="n">from_string</span><span class="p">(</span><span class="n">vk_bytes_from_storage</span><span class="p">,</span> <span class="n">curve</span><span class="o">=</span><span class="n">NIST256p</span><span class="p">)</span>
</span><span id="line-344">        <span class="k">except</span> <span class="ne">Exception</span> <span class="k">as</span> <span class="n">e</span><span class="p">:</span> <span class="c1"># Catch errors from b64decode or VerifyingKey.from_string</span>
</span><span id="line-345">            <span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Failed to decode or reconstruct public key for node &#39;</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&#39;: </span><span class="si">{</span><span class="n">e</span><span class="si">}</span><span class="s2">&quot;</span><span class="p">)</span> <span class="kn">from</span><span class="w"> </span><span class="nn">e</span>
</span><span id="line-346">
</span><span id="line-347">
</span><span id="line-348">        <span class="c1"># Re-serialize node_info exactly as it was when signed</span>
</span><span id="line-349">        <span class="n">node_info_json_bytes</span><span class="p">:</span> <span class="nb">bytes</span> <span class="o">=</span> <span class="n">json</span><span class="o">.</span><span class="n">dumps</span><span class="p">(</span><span class="n">node_info</span><span class="p">,</span> <span class="n">sort_keys</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span><span class="o">.</span><span class="n">encode</span><span class="p">(</span><span class="s2">&quot;utf-8&quot;</span><span class="p">)</span>
</span><span id="line-350">
</span><span id="line-351">        <span class="c1"># The signature stored in etcd</span>
</span><span id="line-352">        <span class="n">stored_signature_bytes</span><span class="p">:</span> <span class="nb">bytes</span> <span class="o">=</span> <span class="n">base64</span><span class="o">.</span><span class="n">b64decode</span><span class="p">(</span><span class="n">stored_signature_base64</span><span class="p">)</span>
</span><span id="line-353">
</span><span id="line-354">        <span class="c1"># Verify the stored signature against the public key from storage and the re-serialized node_info</span>
</span><span id="line-355">        <span class="c1"># This step confirms that the signature matches the public_key stored in node_info itself.</span>
</span><span id="line-356">        <span class="k">try</span><span class="p">:</span>
</span><span id="line-357">            <span class="c1"># Using sigdecode=sigdecode_der because we used sigencode=sigencode_der for signing</span>
</span><span id="line-358">            <span class="k">if</span> <span class="ow">not</span> <span class="n">vk_from_storage</span><span class="o">.</span><span class="n">verify</span><span class="p">(</span><span class="n">stored_signature_bytes</span><span class="p">,</span> <span class="n">node_info_json_bytes</span><span class="p">,</span> <span class="n">sigdecode</span><span class="o">=</span><span class="n">sigdecode_der</span><span class="p">):</span>
</span><span id="line-359">                <span class="c1"># This path should ideally not be reached if verify raises BadSignatureError on failure.</span>
</span><span id="line-360">                <span class="c1"># However, some ecdsa versions might return False.</span>
</span><span id="line-361">                <span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Signature verification failed for node &#39;</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&#39; using its stored public key. &quot;</span>
</span><span id="line-362">                                 <span class="s2">&quot;The data may have been tampered with, or the signature/public key is incorrect.&quot;</span><span class="p">)</span>
</span><span id="line-363">        <span class="k">except</span> <span class="n">BadSignatureError</span><span class="p">:</span> <span class="c1"># This is the expected exception on signature mismatch</span>
</span><span id="line-364">             <span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Signature verification failed for node &#39;</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&#39; using its stored public key. &quot;</span>
</span><span id="line-365">                             <span class="s2">&quot;The data may have been tampered with, or the signature/public key is incorrect. (BadSignatureError)&quot;</span><span class="p">)</span> <span class="kn">from</span><span class="w"> </span><span class="kc">None</span> <span class="c1"># Suppress original context for cleaner error</span>
</span><span id="line-366">
</span><span id="line-367">
</span><span id="line-368">        <span class="c1"># Optional: Additionally, one could re-calculate the signature using self.sk</span>
</span><span id="line-369">        <span class="c1"># and compare it to stored_signature_base64 to ensure self.sk was indeed the key used.</span>
</span><span id="line-370">        <span class="c1"># This is somewhat redundant if vk_from_storage is correctly self.sk.verifying_key.</span>
</span><span id="line-371">        <span class="c1">#</span>
</span><span id="line-372">        <span class="c1"># calculated_signature_bytes: bytes = self.sk.sign_deterministic(node_info_json_bytes, sigencode=sigencode_der)</span>
</span><span id="line-373">        <span class="c1"># if not calculated_signature_bytes == stored_signature_bytes:</span>
</span><span id="line-374">        <span class="c1">#     raise ValueError(f&quot;Integrity check failed for node &#39;{node_id}&#39;: &quot;</span>
</span><span id="line-375">        <span class="c1">#                      &quot;Stored signature does not match signature re-calculated with current registry key. &quot;</span>
</span><span id="line-376">        <span class="c1">#                      &quot;This might indicate data tampering or key mismatch if registry key changed.&quot;)</span>
</span><span id="line-377">
</span><span id="line-378">        <span class="n">logger</span><span class="o">.</span><span class="n">debug</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Signature for node &#39;</span><span class="si">{</span><span class="n">node_id</span><span class="si">}</span><span class="s2">&#39; successfully verified.&quot;</span><span class="p">)</span></div>

</span></code></pre></div>
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